1st April 2011, Google posted about Google motion allowing users to handle Gmail with movements (Web cam needed to use this feature) . So many of you know that it was an April fool prank from Google. You can read more April Fool pranks from Google, Opera, Yahoo etc here. You can view the video here
But some geeks developed the same gestures using Microsoft Kinect sensor to control Gmail using the gestures described by Google.
Here is another video which shows controlling Gmail or Live mail using gestures